Insertion of a Transition Curve |
In Figure 39.1 transition curves are introduced between the straights TV and T'V by shifting the circular curve slightly inwards. The original circular curve is from the point of curvature (P.C.) to the point of tangency (P.T.), with the centre at o has been shifted as SC to CS, with centre at 0'. The transition curves are at the two ends from TS to SC and CS to ST. The following notations have been used.
The distance AB through which the main circular curve is shifted inwards to accommodate the transition curve is called shift (s) or throw. The distance between the original centre O and the shifted centre O' is usually small. It is conventional to represent both the points by one point O as shown in Figure 39.2 which is a simplified diagram of combined curves i.e., circular curve with transition curves at its ends.
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